It is not only the Premier League title that is being removed from Chelsea. Their very identity is being stripped from them. Having come from behind to take a 3-2 lead in the 89th minute they were still incapable of winning.

At present the principal ambition for Carlo Ancelotti's side is to overtake Tottenham Hotspur and seize the last of the Champions League places. Aston Villa, far more spirited than anticipated, always had cause for hope since their opponents' defence was uncertain.

That fallibility would verge on the absurd in the first minute of stoppage time as an ummarked Ciaran Clark headed in a cross from Marc Albrighton. The notion of a Chelsea side unable to attend to the basics confounds every assumption associated with the club since the appointment of José Mourinho as manager.

Even so, this outcome also reflected a spiritedness on Villa's part that was remarkable considering they were taking only their fifth away point of the campaign. The manner in which that outcome was reached angered Chelsea as much as it dismayed them, with Didier Drogba and John Terry arguing with each other at the end.

Such a scene could never have been predicted. The centre-half Richard Dunne was reinstated in Gérard Houllier's line‑up for a first appearance since 6 December but, while that amounted to an upgrade of the Villa defence, it is still true that three goals at home should suffice for a win. Chelsea could cite mitigating circumstances since they were without Alex and Branislav Ivanovic in defence but this fallibility could never have been anticipated, even though the 19-year-old centre-half Jeffrey Bruma was given his first start in the Premier League.

Chelsea's flaw lay in an inability to impose themselves on visitors whose away form has been so fruitless. Given that context, Villa ought to have been devastated when their 2-1 lead was overhauled late in the game. There was an onslaught in progress by then and, after Brad Friedel had made an outstanding save, Drogba still threaded the loose ball past several opponents in the 84th minute.

Momentum then appeared to be sweeping the match towards a Chelsea win. Five minutes later there was still no prize for excellence by Friedel and, after he had denied a Drogba header, Terry followed up to convert with precision.

The lapse that let Villa recover from that was baffling in its lack of the rigour that we take for granted in Chelsea. Presumably they had an offside trap in mind yet the effect was to let the visitors do as they pleased without any interruption. That ought to wound the pride of Ancelotti's line-up but flaws of one sort or another are no longer so startling, even if the course of this particular fixture was beyond anticipation.

This outcome will incite further speculation over Ancelotti's future at Stamford Bridge. This should be absurd, given that his Chelsea side did the Double last season, but managers never feel secure under the Roman Abramovich regime, which saw even Mourinho reaching a point where he thought it best to leave. When they are actually dismissed, there is compensation to be paid but the process is still less expensive than acquiring the young equivalents of footballers such as Frank Lampard and Drogba. And few proprietors are ever keen to embark all over again on the sort of exorbitant purchasing of their early and enraptured days with a club.

Abramovich's opposite number at Villa, Randy Lerner, also has self-sufficiency in mind as a long-term target, even if costly contracts make it impossible for the moment. His side opened here with much enterprise even with Emile Heskey alone in attack. The visitors played well and with some ambition but they had already conceded 22 goals away from home in the league and were sure to reveal that fallibility again. The brittleness, even so, took a strange form.

At the opener James Collins leapt for a high ball by Lampard, made no contact and then collided with Florent Malouda. Lee Mason awarded the penalty, and after the saved effort from Drogba that prevented a win at White Hart Lane, Lampard resumed duty, converting in the 23rd minute. Villa's disquiet was witnessed, too, in seven bookings.

They merited their equaliser, although Paulo Ferreira's poor clearance caused danger that continued with Michael Essien fouling Nigel Reo-Coker for a penalty that Ashley Young slotted home while sending Petr Cech the wrong way in the 41st minute. The visitors took the lead two minutes after the interval. Stewart Downing made space to cross from the right and his cross went beyond Bruma for the excellent Heskey to head home.

Chelsea must have later thought they had put down an uprising by Villa but the old Stamford Bridge dominance had not been re-established.